Boss CE-2 chorus pedal schematic

The Boss CE-2 is a great analog chorus pedal from the late 70s and early 80s. The marketing of the CE-2 was stopped in November 1982, but the pedal was still produced and sold at least until 1990. Even though it's no longer in production there are thousands of these pedals being used by guitarists all over the world -- it's one of the more sought after Boss pedals on the used market.

Specifications:

- 2 Control knobs: Rate and Depth
- Connectors: Input, Output, AC Adaptor
- Input Impedance: 470kOhm
- Signal/Noise Ratio: more than 90dB
- Load Impedance: > 10kOhm
- Recommended AC Adaptor: ACA Series
- Current Draw: 9 mA (DC 9V)
- Weight: 400 grams

The CE-2 was the first compact pedal chorus from Boss. It builds on the legacy of the CE-1 but they are not identical. The circuit is designed around the MN3007 1024 stage BBD (IC3) and the MN3101 clock driver (IC4). The input and output circuits use a uPC4558C IC while the LFO uses a TL022LP op-amp IC.

Other active components:

D1-D5 and D8: 1S2473 or 1S1588 (switching diodes)
D6: RD5.1EB (5.1V Zener diode)
D7: RD11EB (11V Zener diode)
Q1-Q3: 2SC732TM-GR (NPN silicon transistors)
Q4-Q8: 2SC945-P (NPN silicon transistors)
Q9: 2SK30A-Y (Silicon N-channel junction field effect transistor)